1. Field of the Invention
The invention relates in general to the image-processing device, and more particularly to a scanning apparatus
2. Description of the Related Art
With the constant progress of technology, the integration and application of multimedia has become the emphasized part of current development. Various kinds of applications of multimedia have been developed in order to present data again in form of multimedia, which satisfies consumers' diversified need. So far, the scanner is undoubtedly one of the most powerful tools to process the still image. Due to the maturity of scanning technology and the rise of high-speed interface, scanners have become popular among the professional image workers and the ordinary users in recent years
A scanner is used for scanning the paper documents and then transforming and saving the image as the digital files. It is a convenient way for users to spread, arrange and keep the original drafts. In order to present the original matter of those paper documents completely, the scanning quality of the scanners are especially important. Referring to FIG. 1, a block diagram illustrating a conventional scanner is shown. The conventional scanner includes a movable chassis 110 and a main board 150 fixed on the body of the scanner. The chassis 110 includes a charge-coupled device (CCD) module 115 for detecting a light signal. An application-specific integrated circuit (ASIC) 151 and an analog front end (AFE) processor 153 are arranged and disposed on the main board 150, for controlling the charge charge-coupled device module 115, and receiving the light signal and converting the light signal to digital form, respectively.
During scanning, the chassis 110 of the scanner moves along with the complete length of original document, and the charge-coupled device module 115 simultaneously detects the light signal, which is reflected or transmitted from the scanned document. The light signal corresponding to red light (R), green light (G) and blue light (B) in analog form is so called light analog signal RGB. After the charge-coupled device module 115 receives the light analog signal RGB, the application-specific integrated circuit 151 obtains the light analog signal RGB in accordance with the control signal (CTRL), and then proceeds the following procedures of image processing. Especially, the light analog signal RGB can not be processed by a computer directly, so that the light analog signal RGB is converted to a digital form by the analog front end processor 153. Afterward, the light digital signal DOS is transmitted through the BUS to the application-specific integrated circuit 151 through the BUS for the following image processing.
Additionally, the drive motor 155 and memory 157 are disposed on the main board 150. The drive motor 155 controls the movement of the chassis 110 in response with the command, which is transmitted from the application specific integrated circuit 151, such as the command of specific start-stop movement. The memory 157 is a data buffer area for storing scanning data temporarily.
In the practical operation, since the analog front end processor 153 and application-specific integrated circuit 151 are both disposed on the main board 150, there are numerous connecting lines between the main board 150 and the chassis 110. In addition to three light signal lines, each of which is for one of the three primary color (RGB) signals there are still other connecting lines for transmitting the various signals, such as the Φ1 and Φ2 signals of CCD control signal (CTRL), the reset signal, the power signal, and the grounding signal (GND). Please refer to FIG. 2, showing a layout illustrating a charge-coupled device module (CCD) manufactured by Sony Inc. The CCD product of Sony, commercially named ILX558K, requires twelve input/output pins and the numerous signal lines in the circuit connection, resulting in a high manufacture cost. Moreover, the conventional TTL/CMOS electronic standard is used as the controlling interface, in which a high voltage level, such as 5V and 3.3V, is applied, so that the electric power is consumed magnificently and the data transmission quantity is hard to be improved. Furthermore, the light analog signal RGB transmitted from the charge-coupled device module 115 to the main board 150 is easy to be interfered by the environmental factors, so that it impacts on the scanning quality and also may cause the electromagnetic interference (EMI) during the scanning operation. The drawbacks described above have the direct influence on the competitiveness of the commercial product, especially the scanner made for high scanning resolution. Accordingly, it is one of the important issues to improve the scanning quality and decrease the manufacturing cost.